Hearing aids are portable hearing instruments for use by the hard of hearing. In order to meet the numerous individual requirements, different hearing aid types are provided, such as behind the ear (BTE) hearing aids, in the ear (ITE) hearing aids, and concha hearing aids. The hearing devices listed by way of example are worn in the outer ear or in the auditory canal. However, bone conduction hearing aids, implantable or vibrotactile hearing aids are also commercially available. In these cases, the damaged hearing is stimulated either mechanically or electrically.
The basic components of a hearing aid are essentially an input transducer, an amplifier and an output transducer. The input transducer is generally a sound receiver, e.g. a microphone, and/or an electromagnetic receiver such as an induction coil. The output transducer is mainly implemented as an electroacoustic transducer, e.g. a miniature loudspeaker, or as an electromechanical transducer such as a bone conduction earphone. The amplifier is usually incorporated in a signal processing unit. This basic design is shown in FIG. 1 using the example of a behind the ear hearing aid. Installed in a hearing aid housing 1 for wearing behind the ear are one or more microphones 2 for picking sound from the environment. A signal processing unit 3 which is likewise incorporated in the hearing aid housing 1 processes the microphone signals and amplifies them. The output signal of the signal processing unit 3 is transmitted to a loudspeaker or earphone 4 which outputs an audible signal. The sound is in some cases transmitted to the wearer's eardrum via a sound tube which is fixed in the auditory canal using an otoplastic. The hearing aid and in particular the signal processing unit 3 are powered by a battery 5 likewise incorporated in the hearing aid housing 1.
The trend of the latest developments is for hearing aids to be increasingly trainable on an individual basis, e.g. for the hearing aid wearer to have ever more interactive control over his hearing aid or rather its adjustment. This creates problems in some circumstances if, because of the large number of adjustment options, the hearing aid wearer loses control of the adaptive adjustments. This can eventually result in the hearing aid being completely out of adjustment.
Patent specification DE 42 06 084 C1 discloses a hearing aid with a means of electronically adjusting a transmission parameter. On the hearing aid there is additionally provided a reset circuit acting on the means of electronically adjusting the transmission parameter. Using this reset circuit, the means can be reset to an initial state (starting position). Such a resetting takes place in particular when the hearing aid's ON/OFF switch is actuated. However, it is also possible for resetting to be initiated when a manually actuatable switch is erroneously operated. This means that the hearing aid automatically reverts to an initial state of the transmission path both in the event of erroneous operation and when it is switched on. Such initial settings are known from other electronic devices and are preset in the factory for particular device types and also stored in a memory provided for that purpose.